The Antiproliferative Effect of Moringa oleifera Crude Aqueous Leaf Extract on Human Esophageal Cancer Cells

Abstract

Esophageal cancer (EC) is commonly diagnosed in South Africa (SA), with high incidences occurring in SA's black population. Moringa oleifera (MO), a multipurpose tree, is used traditionally for its nutritional and medicinal properties. It has been used for the treatment of a variety of ailments, including cancer. We investigated the antiproliferative effect of MO crude aqueous leaf extract (MOE) on a cancerous esophageal cell line (SNO). SNO cells were exposed to a range of MOE dilutions to evaluate cytotoxicity (MTT assay). Oxidative stress was determined using the TBARS assay. The comet assay was used to assess DNA damage. We then determined cell death mechanisms by measuring phosphatidylserine (PS) externalization (flow cytometry), caspase-3/7 and caspase-9 activities, and adenosine triphosphate (ATP) levels (luminometry). Protein expression of Smac/DIABLO and PARP-1 was determined by western blotting. SNO cells were treated with a range of MOE dilutions to obtain an IC₅₀ value of 389.2 μg/mL MOE (24 h), which was used in all subsequent assays. MOE significantly increased lipid peroxidation (P < .05) and DNA fragmentation (P < .0001) in SNO cells. The induction of apoptosis was confirmed by the increase in PS externalization (P < .0001), caspase-9 (P < .05) and caspase-3/7 (P = .22) activities, and decreased ATP levels (P < .0001). MOE significantly increased both the expression of Smac/DIABLO protein and cleavage of PARP-1, resulting in an increase in the 24-kDa fragment (P < .001). MOE possesses antiproliferative effects on SNO EC cells by increasing lipid peroxidation, DNA fragmentation, and induction of apoptosis.